test(media-dedup): add missing coverage for Discord media dedup wiring

Cover three integration points where media dedup could silently regress:
- trimMessagingToolSent FIFO cap at 200 entries
- buildReplyPayloads media filter wiring (new test file)
- followup-runner messagingToolSentMediaUrls filtering

src/auto-reply/reply/agent-runner-payloads.test.ts

@@ -0,0 +1,46 @@
+import { describe, expect, it } from "vitest";
+import { buildReplyPayloads } from "./agent-runner-payloads.js";
+
+const baseParams = {
+  isHeartbeat: false,
+  didLogHeartbeatStrip: false,
+  blockStreamingEnabled: false,
+  blockReplyPipeline: null,
+  replyToMode: "off" as const,
+};
+
+describe("buildReplyPayloads media filter integration", () => {
+  it("strips media URL from payload when in messagingToolSentMediaUrls", () => {
+    const { replyPayloads } = buildReplyPayloads({
+      ...baseParams,
+      payloads: [{ text: "hello", mediaUrl: "file:///tmp/photo.jpg" }],
+      messagingToolSentMediaUrls: ["file:///tmp/photo.jpg"],
+    });
+
+    expect(replyPayloads).toHaveLength(1);
+    expect(replyPayloads[0].mediaUrl).toBeUndefined();
+  });
+
+  it("preserves media URL when not in messagingToolSentMediaUrls", () => {
+    const { replyPayloads } = buildReplyPayloads({
+      ...baseParams,
+      payloads: [{ text: "hello", mediaUrl: "file:///tmp/photo.jpg" }],
+      messagingToolSentMediaUrls: ["file:///tmp/other.jpg"],
+    });
+
+    expect(replyPayloads).toHaveLength(1);
+    expect(replyPayloads[0].mediaUrl).toBe("file:///tmp/photo.jpg");
+  });
+
+  it("applies media filter after text filter", () => {
+    const { replyPayloads } = buildReplyPayloads({
+      ...baseParams,
+      payloads: [{ text: "hello world!", mediaUrl: "file:///tmp/photo.jpg" }],
+      messagingToolSentTexts: ["hello world!"],
+      messagingToolSentMediaUrls: ["file:///tmp/photo.jpg"],
+    });
+
+    // Text filter removes the payload entirely (text matched), so nothing remains.
+    expect(replyPayloads).toHaveLength(0);
+  });
+});

src/auto-reply/reply/followup-runner.test.ts

@@ -257,6 +257,47 @@ describe("createFollowupRunner messaging tool dedupe", () => {
     expect(onBlockReply).not.toHaveBeenCalled();
   });
 
+  it("drops media URL from payload when messaging tool already sent it", async () => {
+    const onBlockReply = vi.fn(async () => {});
+    runEmbeddedPiAgentMock.mockResolvedValueOnce({
+      payloads: [{ mediaUrl: "/tmp/img.png" }],
+      messagingToolSentMediaUrls: ["/tmp/img.png"],
+      meta: {},
+    });
+
+    const runner = createFollowupRunner({
+      opts: { onBlockReply },
+      typing: createMockTypingController(),
+      typingMode: "instant",
+      defaultModel: "anthropic/claude-opus-4-5",
+    });
+
+    await runner(baseQueuedRun());
+
+    // Media stripped → payload becomes non-renderable → not delivered.
+    expect(onBlockReply).not.toHaveBeenCalled();
+  });
+
+  it("delivers media payload when not a duplicate", async () => {
+    const onBlockReply = vi.fn(async () => {});
+    runEmbeddedPiAgentMock.mockResolvedValueOnce({
+      payloads: [{ mediaUrl: "/tmp/img.png" }],
+      messagingToolSentMediaUrls: ["/tmp/other.png"],
+      meta: {},
+    });
+
+    const runner = createFollowupRunner({
+      opts: { onBlockReply },
+      typing: createMockTypingController(),
+      typingMode: "instant",
+      defaultModel: "anthropic/claude-opus-4-5",
+    });
+
+    await runner(baseQueuedRun());
+
+    expect(onBlockReply).toHaveBeenCalledTimes(1);
+  });
+
   it("persists usage even when replies are suppressed", async () => {
     const storePath = path.join(
       await fs.mkdtemp(path.join(tmpdir(), "openclaw-followup-usage-")),